Buggy code:
public class PluginActionSetBuilder extends PluginActionBuilder { public static final String TAG_ACTION_SET = "actionSet" ; public static final String ATT_PULLDOWN = "pulldown" ; private PluginActionSet actionSet ; private IWorkbenchWindow window ; private ArrayList adjunctContributions = new ArrayList ( 0 ) ; public PluginActionSetBuilder ( ) { } protected ActionDescriptor createActionDescriptor ( IConfigurationElement element ) { } protected BasicContribution createContribution ( ) { } public static IContributionItem findInsertionPoint ( String startId , String sortId , IContributionManager mgr , boolean startVsEnd ) { } static void processActionSets ( ArrayList pluginActionSets , WorkbenchWindow window ) { } protected void processAdjunctContributions ( ) { } protected void readActionExtensions ( PluginActionSet set , IWorkbenchWindow window ) { } private static class ActionSetContribution extends BasicContribution { private String actionSetId ; private WorkbenchWindow window ; private ArrayList adjunctActions = new ArrayList ( 0 ) ; public ActionSetContribution ( String id , IWorkbenchWindow window ) { } protected void addGroup ( IContributionManager mgr , String name ) { } public void contribute ( IActionBars bars , boolean menuAppendIfMissing , boolean toolAppendIfMissing ) { } protected void contributeAdjunctCoolbarAction ( ActionDescriptor ad , ActionSetActionBars bars ) { } protected void contributeCoolbarAction ( ActionDescriptor ad , ActionSetActionBars bars ) { String toolBarId = ad . getToolbarId ( ) ; String toolGroupId = ad . getToolbarGroupId ( ) ; if ( ( toolBarId == null ) && ( toolGroupId == null ) ) return ; String contributingId = bars . getActionSetId ( ) ; CoolBarManager coolBarMgr = ( ( CoolItemToolBarManager ) ( bars . getToolBarManager ( ) ) ) . getParentManager ( ) ; if ( ( ( toolBarId == null ) || ( toolBarId . equals ( "Normal" ) ) ) || ( toolBarId . equals ( "" ) ) ) { toolBarId = contributingId ; } if ( ! ( toolBarId . equals ( contributingId ) ) ) { <START_BUG> if ( ! ( coolBarMgr . isValidCoolItemId ( toolBarId ) ) ) { <END_BUG> toolBarId = contributingId ; } else { adjunctActions . add ( ad ) ; return ; } } PluginAction action = ad . getAction ( ) ; PluginActionCoolBarContributionItem actionContribution = new PluginActionCoolBarContributionItem ( action ) ; CoolItemToolBarManager activeManager ; CoolBarContributionItem cbItem = ( ( CoolBarContributionItem ) ( coolBarMgr . find ( toolBarId ) ) ) ; if ( cbItem == null ) { activeManager = ( ( CoolItemToolBarManager ) ( bars . getToolBarManager ( ) ) ) ; cbItem = activeManager . getCoolBarItem ( ) ; cbItem . setVisible ( true ) ; IContributionItem refItem = findCoolItemInsertionPoint ( toolBarId , coolBarMgr ) ; if ( refItem == null ) { coolBarMgr . add ( cbItem ) ; } else { coolBarMgr . insertAfter ( refItem . getId ( ) , cbItem ) ; } } activeManager = cbItem . getToolBarManager ( ) ; IContributionItem groupMarker = activeManager . find ( toolGroupId ) ; if ( groupMarker == null ) { activeManager . addBaseGroup ( toolGroupId ) ; } activeManager . addToGroup ( toolGroupId , contributingId , actionContribution ) ; } protected void insertMenuGroup ( IMenuManager menu , AbstractGroupMarker marker ) { } public IContributionItem findCoolItemInsertionPoint ( String sortId , CoolBarManager mgr ) { } public boolean isAdjunctContributor ( ) { } protected void insertAfter ( IContributionManager mgr , String refId , IContributionItem item ) { } } }

Fix:
if ( ! ( coolBarMgr . isValidCoolItemId ( toolBarId , window ) ) ) {